1. Technical Field
The present disclosure relates to an inkjet printer having a nozzle cap that covers the nozzle surface in order to keep the nozzle surface of the inkjet head from drying out. The disclosure relates more particularly to an inkjet printer having a cap moisture retention mechanism that keeps the inside of the nozzle cap desirably moist.
2. Related Art
If moisture evaporates from the ink in the nozzles of the inkjet head while the inkjet printer is waiting for the next print job or printer power is off and the ink viscosity increases, ink droplet ejection problems can occur during the next print job. To prevent this, a nozzle cap is placed over the nozzle surface of the inkjet head when not printing to keep the nozzle surface sealed so that moisture does not evaporate, that is, keeps the nozzles from drying out.
While printing with the inkjet head, the nozzle cap is not capping the nozzle surface and is left open. If this condition continues for long, moisture also evaporates from inside the nozzle cap, and viscous ink can build up in the cap. If the nozzle cap then covers the nozzle surface of the inkjet head after printing ends, the glycerine, diethylene glycol, or other moisturizing agent in the high viscosity ink accumulated in the nozzle cap will absorb moisture from inside the nozzles of the inkjet head. This promotes a further increase in ink viscosity inside the nozzles, and can lead to clogged nozzles and ink droplet ejection problems.
To prevent such problems, Japanese Unexamined Patent Appl. Pub. JP-A-2001-18408 and JP-A-2009-226719 teach inkjet recording devices having a moisture retention means that supplies a moisturizing fluid into the nozzle cap, or a cleaning means that supplies a cleaning fluid into the nozzle cap to remove the accumulated viscous ink.
Providing space sufficient to install such a moisture retention means or cleaning means is generally difficult, however, in small inkjet printers. Providing a moisture retention means or cleaning means also increases product cost.
Using inkjet printers to print endorsements on the back of checks, for example, is also conceivable. A stationary inkjet line head could be disposed to a fixed position on the check conveyance path, for example, in order to print on the back of checks conveyed through a check conveyance path.
When an inkjet line head disposed to a fixed position is used, the nozzle cap is disposed opposite the nozzle surface with the check conveyance path or other media conveyance path therebetween, and the nozzle cap must be moved across the media conveyance path to cap the nozzle surface. This can be done by rendering an opening in the media guide or platen that is disposed opposite the nozzle surface of the inkjet head, and moving the nozzle cap to and away from the nozzle surface through this opening.
However, if an opening for moving the nozzle cap in and out is rendered in the media guide, the edge of the media passing thereby could catch on the edge of the opening, and paper jams can easily result. If a paper jam occurs at the printing position where the nozzle surface is positioned to the media path, paper dust may clog the nozzles of the inkjet head, undesirably resulting in ink droplet ejection problems or ink droplets smearing the surface of the conveyed media, for example.